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G. E. STACK.

MOTOR CONTROL SYSTEM. APPLICATION mm JULY 31.1913.

Patnted Dec. 23,1919.

Inventor: George E. St, ack

His ALLorne UNITED STATES PATENT @FFEEE.

GEORGE E. STACK, OF BALLSTON, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMBANY, A CORPORATION OF NEW YORK.

MOTOR-CONTROL SYSTEM.

Specification of Letters Patent. Patented Dec. 23, 1919..

Application filed July 31, 1918. Serial No. 247,478.

tems, of which the following is a specification.

'My invention relates to the control of electric motors and has for its object the provision of means whereby an electric motor maybe started, stopped and generally controlled in a reliable, simple and efficient manner. My invention relates more specifically to the control of variable speed motors for use in 'applications'where it is desirable upon restarting after stopping to have the motor automatically come to the speed which it had before stopping. In one embodiment of my invention I employ what is known as a push button controlbyy which is meant control in which any of the operations is accomplished automatically upon the operation of a push button. Ordinarily there is provided a starting push button which brings the motor to its normal running speed; a stopping button for stopping the motor; a fast button which speeds up the motor above normal button for decreasing the speed of the motor. All of these buttons may not in all cases be necessary. In carrying out my invention in one form I provide means whereby if the motor should be running at a certain speed and the motor is stopped, for/instance by pressing-a stop button, upon again starting the motor, as for instance by pressing the start button, the motor will'automatically be brought up to the speed whichit had before stopping. p

In the specific arrangement which I have disclosed I employ'a pilot motor for oper- I ating the control mechanism for both the starting and the speed variation and provide means whereby, upon restarting, the pilot motor will operate the control mechanism when the start button is pressed until the speed is reached which the motor had be-.

fore stopping. The specific means whereby this is accomplished consists of a control member operated by a pilot motor for effecting the starting and speed variation and an auxiliary member, which, when it is engaged by the control ,member, stopsthe movement of the control m mber 9 that d a slow there can be no further progress through the start button. In this position, however, the members are locked together so that if either the slow or fast button should 'bepresse'd the pilot motor will again operate-to either slow down or speed up the motor. IVhen the 'stop button is pressed the members will be unlocked leaving the auxiliary member where it happens to be and moving the control member back to the initial position.

Upon again pressing the start button the control member will therefore move until it engages the auxiliary member which, of course,w1ll correspond to the speed at which the motor was running before stopping.

Other objects and purposes of my invention will appear in the course of the following specification in which I have shown my invention embodied in concrete form for purposes of illustration. I

In the accompanying drawingFigure 1 is a diagrammatic View of the system as a whole and, Figs. 2 and 3 are details of the locking mechanism. Referring to the drawing. A-represents the armature, F the series field, and F a shunt field of the electric motor to be controlled. I have shown this motor as being reversible through the reversing switch 10. R, and R represent sections of starting resistance-which are cut out of circuit by electromagnetic switches or contactors 11, 12 and 13. 14: is a line contactor for closing the motor circuit initially. 1 5 and 16 are field protective contactors for opening the motor circuit in case the field circuit is broken or otherwise interrupted. 17 is a reshunt contactors when a push button is pressed and makes a maintaining circuit for gearing 21, so as to consecutively engage the contacts 22,23 and 24 which energize the contactors 11, 12 and 13 respectively, to cut out the section of resistance. This arm also engages a'segment 25 which is connected by a conductor 26 with field protective contactor 16 and field F. F. R. represents the field resistance which causes the variation in speed of the motor after the motor has come up to its normal running speed. This relay contactor for closing the circuit of the sistance is provided with contacts 27 en-' gaged by the control arm 18 so that as the arm passes 011' of the starting section a continuous movement will bring it into engagement with the field contacts and insert field resistance. Pilot motor 20 is reversible, being provided with two field windings f and f which are closed by thev contactors '28 and 29 respectively. In other'words, when the contactor 28 closes, the pilot motor will. operate in one direction, and when the con-- tactor 29 is closed, the pilot motor Wlll opcrate in the reverse direction.

In order to provlde that when the motor is stopped with the control arm on any of the field resistance contacts 27, upon restarting the arm will be brought back .to that point, I provide the auxiliary arm 30 which is pivoted concentrically with themaln con,

trol member 18. This arm is provided with two contacts 31 and'32 engagmg contact segments 33 and 34 respectively and 1s arranged to remain in any position in which j it is left. It is likewise provided with means for locking itself to the control arm 18 when the two arms come together when the arm 18 is beneath the arm 30. The arrangement whereby this is accomplished is shown in Figs. 2 and 3,'from which it w1ll be seen that locking arm 35 is pivoted to the arm' and has onits free end a hooked .por tion 36 provided with a roller 37. The arm is-provided with a lifting core '35 for electromagnet 35 which lifts the core against the tension of spring 38. The atrangement is such thatas the arm 18 comes under the arm 30 the roller 37' rolls on the 'arm 18 until it drops over the edge, as shown in Fig. 3 and locks the arm 18 against independent movement. ',The projection 39 prevents the arm 18 from .ever going beyond the arm 30. The arm30 is likewise provided'with a switch arm 40 having a projection 41 which is engaged by a roller 44 on the arm 18'to 'move the switch arm I out of engagement with the contact 42- and into engagement with the contact 43. The;

result is that when the amt-.118 passes under the arm 30 the switch 40 is operated to break contact at 42 to stop the pilot motor and makes contact at 43 which is in the cir-'- cuit of the magnet 35". The magnet 35" is not at this time energized however, there fore the two arms remain locked together. When, however, the'st0p button is pressed the magnet 35 is energized and the armsare unlocked so that the arm 18 may return .to its initial position leaving the arm 30 where it stands. The roller 44 at theend of the arm 18 in the initial position of the arm engages an angular switch arm 45. This switch insures that the arm is brought back to starting position before the motor circuit can be closed after the stopping of the motor. There are also provided switches 46, 47 and 48 which are operated by a roller 49 on arm 30 at the positions shown forpurposes hereinafter described.

As thus constructed and arranged the operation of my system is as follows: With the parts in the position shown in Flg. 1 and the switch S closed, by closing the switches S and 10 the contactors 15, 16 and the field winding F will be energized from the positive side of the line, through the switch S winding. of contactor 15, field F, contactor 16 to the segment 25, thence to the .side of the line. The contactor 17 will now close and make a maintaining circuit for itself at interlocking contact 58, which circuit will be independent of the -startbutton. The closing of contactor 17 completes the circuit for the line contactor ,14 throu h the contacts of contactor 17 back. to line through conductor 57. The closing of contactor 14 closes the circuit through the main motor. armature and resistance R, R and ,R; The closing of contactorf14 also com pletes a circuit for the Jwindingof contactor 28 to close the circuit of the pilot motor,

the circuit being as followsg from the posi- ,tlve slde of the line through conductor 51, windlng of contactor 28, through the interlock 59 on contactor 14, thence through the segment 33, contact '31, through the switch 40, thence to conductor 50 and back to the other side of the line.- The closing of contact0r'28 completes the circuit forthe'pilot motor through the field f resistancer, the circuit being from the positive side of the line, conductor 51,;th'rough the contacts of contactor 28, field f and armature of the pilot motor, resistancer and conductor 50' to the negative side of the line. The pilot. motor will now. start and move the*arm 18 This energizes the shunt over the contacts-22, 23 and 24 successively to'energize thecontact'ors 11, 12 and 13 and short circuit resistance sections R, R and R until the motor finally comes up tonor- 30 has been left in the position shown, the arm 18 will continue to move after it leaves contact 24and segment-25. vWhen the arm 18 comes underthe' arm '30 the switch 40 is operated to deenergize the contactor 28 and stop the pilot motor. The switch 40 is also moved to make contact a 43 $9 as $001088- .mal running speed. Assuming that the arm further, one ofthe fast buttons ispressed whereupon the contactor 28 will be again energized to start the'pilot'motor for forward movement. In this movement the arm 18 will engage the projection 39 on arm 30 and move the latter forward with it. This movement may be continued'so long as the fast button is pressed until the switch 48 is reached, which will stop the pilot motor.

If the stop button should now be pressed with the motor running at its highest speed the arm 18 will be released from the arm 30 and returned to its initial position.- Upon again restarting, the arm 18 will be brought up to this highest speed. s

Assuming that the motor is running at the highest. speed, or for that matter at any speed above normal, if one of the slow buttons is pressed, the contactor 29 will be energized through the conductor. 60, switch 46 and switch 15, which has been closed on contact 61 in the forward movement of the arm 18, and conductor 52. This will cause the pilot motor to be energized through the field winding f so as to reverse the pilot motor. Since the two arms are now locked together they will both move backward and ,slow down the motor So long as the slow button is pressed this slowing operation may b 'carried on until the switch '47 is' opened by the roller 49 on the arm 80. which opens contactor 29. Switch 46 is emergencyswitch in series with switch 47.

It'will thus be seen that I. have provided a motor control system of the push button .typev in which a motor may be brought to anyspeed by-the operation of push buttons, and upon being stopped by a push. button and restarted, will'return to the speedwhich itv had before stopping While I'have' described myinvention as embodied in concrete form and as operating in a specific manner in accordance with the provisions of the'patent statutes, it should be understood that I do not limitmy inven; tion thereto, slnce' various modifications. thereof will suggest themselves to those skilled in the art withoutdeparting from .the spirit of 'my inventiomthe scope of.

which is set forth in thean'nexed claims' What I claim as new and desire to secure by Letters Patent of the United S ates, is: 1 The combination with an electric motor of means for starting the same, means for varying the speed after the starting' had before. stopping.

ing speed, and means whereby upon re-v starting the motor after stopping it will 1 automatically return to the speedwhich it 2. The combination with an electric mo- ,tor of means for starting thesame, means for varylngthe speed of the motor including a manually operated normally'inopera- 'tive' switch for gradually increasing the speed of the. motor and a. similar switch for gradually decreasing the'speed and means whereby upon restarting the motor after stopping it will automatically return to the speedwhich it had before stopping. The combination 'withan' electric motor of, means for starting the same, a resistance member for varyingthe speed of the motor,

a pilot motor for. operating thesame to various positions to increase and-decrease the speed of the motor and means whereby upon restarting the motor after stopping it will automatically return to the speed: which it had before stopping.

"4:. The combinatlon with an electric motor of starting-and speed regulating mechanism, a pilot motor for operating the same to various positions, to start the motor and a increase and decrease its speed and means whereby upon restarting the motor after stopping it will automatically return. to the 7 speed which it had before stopping..

5. The combination. with-an electric-mo:

tor, of a starting mechanism therefor, a

pilot motor for operating thesame, speed regulating mechanism operated by the pilot motort6 various positions to increase and decrease. th speed of the motor after the startingmechanism is operatedand means whereby upon restarting the motor after stopping it will automatically return to the speed which it had-before stopping.

6. The combination with an electric motonof a pivoted startingmember therefor, a1 pllotmotor forfoperating the same, an independently movable member operated by the pilot motor to various positions to lim t the movement of the starting member and means whereby upon restarting the motor after stopping it will automatically return to the speed which it'had before stopping.

-7. The combination 'with an electric motor of a pivoted f-startingand speed varying member therefor; apilot motor for operating the same, an independently'movable member operated ibythe' pilot motorfor limiting the 'movementof the starting "member after the starti'ngqmemberkhas' completed its starting "movement and, means whereby upon restarting theimotor after stopping it will auto- I matically return to the speed which it had be fore stopping.

8'. The combination with an electric motor. of a starting and speed varying member therefor, a pilot motor for operating the same, an independently movable member for limiting the movement of the starting member after the starting member has completed its starting movement and means whereby upon restarting the motor after stopping it will automatically return to the speed which it had before stopping.

9. The combination with an electric motor of a controlling member therefor, a pilot motor for operating the same, an auxiliary member arrangedto be engaged by the controlling member to stop the pilot motor and lock the two members together, and independently controlled means for again starting the pilot motor to move both members,

so as to establish a new limit of operation for the pilot motor.

10. The combination with an electric motor of a controlling member therefor, of a pilot motor for operating the same, an auxiliary member arranged to be engaged by the controlling member to stop the pilot motor and lock the two members together, and means for unlocking the members and causing the controlling member to move backward from the locking position.

11. The combination with an electric motor of a controlling member therefor, a pilot motor for operating the same, an independently movable member arranged to be engaged by the controlling member and denergize the pilot motor and independently operated means for restarting the pilot motor.

12. The combination with an electric motor of a controlling member therefor, an independently movable member arranged to be engaged by the controlling member and moved forward thereby; after engagement, means for locking the members together so that they will move backward tOgBthBIfilld independently controlled means for unlocking the members so that the controlling member may be moved backward independently.

13. The combination with an electric motor of a controlling member therefor, a pilot motor for operating the same, independent switches for starting and stopping the pilot motor, an independently movable member arranged to be engaged by the controllin member to stop the pllot motor and a switch for energizing the pilot motor in a reverse direction to cause the controlling member to return.

14. The combination with an electric motor of a controlling member therefor, a pilot motor for operating the same, an auxiliary member arranged to be engaged by the controlling member so that the' members will move forward together after engagement and having means for deenergizing the pilot motor, a switch for energizing the pilot motor so that the controlling member will be motor, means for locking the members together so that they will move backward together, a switch for energizing the motor to cause such backward movement and aswitch for unlocking the members and causing the controlling member to return independently.

16. The combination with an electric motor of a starting and speed varying member therefor, a pilot motor for operating the same, a switch for energizing the pilot motor to move the member to start the motor, an auxiliary member movable over the speed varying positions and arranged to be engaged by the controlling member to stop the pilot motor, means for causing the auxiliary member to always move forward with the controlling member after engagement, means for locking the members together upon engagement so that they will move backward together, a switch for energizing the motor 1 to cause the forward movement of the two members and a switch for unlocking the members and causing the control member to return independently.

In witness whereof, I have hereunto set my hand this 27th day of July, 1918.

GEORGE E. STACK. 

